Adolescents have shifted into the focus of global policy, reflecting their central role in achieving the 2030 Sustainable Development Goals (SDGs) [1Ki-moon B. Sustainability--engaging future generations now.Lancet. 2016; 387: 2356-2358Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar, 2Every Woman Every ChildThe global strategy for women's, children's and adolescents' health (2016-2030).2015Google Scholar]. With 1.2 billion adolescents aged 10–19 years, the largest adolescent population in human history, representing more than 16% of the world's population, investments in adolescent health and well-being will yield benefits not only for adolescents now but also for their adult lives and future generations [3United Nations, Department of Economic and Social Affairs, Population DivisionMonitoring global population trends.http://www.un.org/en/development/desa/population/publications/index.shtmlDate: 2017Date accessed: December 1, 2018Google Scholar, 4Patton G.C. Sawyer S.M. Santelli J.S. et al.Our future: A Lancet commission on adolescent health and wellbeing.Lancet. 2016; 387: 2423-2478Abstract Full Text Full Text PDF PubMed Scopus (1519) Google Scholar]. The SDGs, the Global Strategy for Women's, Children's and Adolescent's Health, the Global Accelerated Action for the Health of Adolescents, and the Lancet Commission on Adolescent Health and Well-Being all emphasize the need for high-quality data to identify priorities and monitor progress in adolescent health [2Every Woman Every ChildThe global strategy for women's, children's and adolescents' health (2016-2030).2015Google Scholar, 4Patton G.C. Sawyer S.M. Santelli J.S. et al.Our future: A Lancet commission on adolescent health and wellbeing.Lancet. 2016; 387: 2423-2478Abstract Full Text Full Text PDF PubMed Scopus (1519) Google Scholar, 5Inter-Agency and Expert Group on Sustainable Development Goal IndicatorsRevised list of global sustainable development goal indicators.2017Google Scholar, 6World Health OrganizationGlobal accelerated action for the health of adolescents (AA-HA!): Guidance to support country implementation. World Health Organization, Geneva, Switzerland2017Google Scholar]. In response, there have been investments by United Nations (UN) agencies, country governments, and academia and other stakeholders around indicator development and data collection. These efforts have, however, largely occurred in silos with little harmonization across initiatives, resulting in duplication of work and inefficiencies, and yet a persistent lack of quality data required to inform effective, efficient, and accountable investments for adolescent health and well-being [[7]Azzopardi P. Kennedy E. Patton G. Data and indicators to measure adolescent health, social development and well-being. Innocent Research Briefs 2017-04; Methods: conducting research with adolescents in low- and middle-income countries, No. 2. UNICEF Office of Research - Innocenti, Florence, Italy2017Google Scholar]. To harmonize measurement efforts and improve the quality and coverage of adolescent health data, World Health Organizations' Departments for Maternal, Newborn, Child and Adolescent Health and Reproductive Health and Research, in collaboration with the UN H6 partnership agencies, [[2]Every Woman Every ChildThe global strategy for women's, children's and adolescents' health (2016-2030).2015Google Scholar] have established an Advisory Group on “Global Action for Measurement of Adolescent health–GAMA.” The Global Action for Measurement of Adolescent Health (GAMA) Advisory Group was established alongside the Child Health Accountability Tracking (CHAT) Advisory Group, both following the example of the Mother and Newborn Information for Tracking Outcomes and Results (MoNITOR) Advisory Group, established in 2015 [8Moran A.C. Moller A.B. Chou D. et al.‘What gets measured gets managed’: Revisiting the indicators for maternal and newborn health programmes.Reprod Health. 2018; 15: 19Crossref PubMed Scopus (11) Google Scholar, 9Moller A.B. Newby H. Hanson C. et al.Measures matter: A scoping review of maternal and newborn indicators.PLoS One. 2018; 13: e0204763Crossref PubMed Scopus (27) Google Scholar]. Together, the GAMA, CHAT, and MoNITOR Advisory Groups aim to improve health measurement and reporting during key phases of the life course so as to ensure accountable action. The GAMA Advisory Group consists of 12 experts, one MoNITOR representative, and four young professionals (Table 1), selected through a competitive process. Members were selected based on their technical expertise including adolescent health epidemiology, monitoring and evaluation, survey design, indicator development, and health information systems implementation. Further considerations in the selection were to ensure broad expertise across the main health issues of adolescents, geographic diversity, and gender balance. Members of the Advisory Group were appointed to serve for an initial term of 2 years.Table 1Global Action for Measurement of Adolescent health (GAMA) Advisory Group membersNameGenderCountry of originAffiliationCo-chairs Peter AzzopardiMAustraliaBurnet Institute, Melbourne; Wardliparingga Aboriginal Research Unit, Adelaide; Centre for Adolescent Health, University of Melbourne Mariame Guèye BaFSénégalUniversity Cheikh Anta Diop of Dakar, Faculty of Medicine, Pharmacy and Odontology/Gynecology and Obstetrics Clinic, University Teaching Hospital A. Le Dantec, Dakar Lucy Fagan (young professional)FUnited KingdomUN Major Group for Children and YouthExperts Emmanuel AdebayoMNigeriaFederal University of Agriculture, Abeokuta Krishna BoseFIndiaBill & Melinda Gates Institute for Population and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore Saeed DastgiriMIranTabriz Health Services Management Research Center, Tabriz University of Medical Sciences, Tabriz Jane FergusonFCanada/SwitzerlandIndependent Consultant on adolescent health and development Ann HagellFUnited KingdomAssociation for Young People's Health, London Joanna InchleyFUnited KingdomMRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Glasgow Laura KannFUSAIndependent Consultant Sunil MehraMIndiaMAMTA Health Institute for Mother and Child, New Delhi Elizabeth SaewycFCanadaSchool of Nursing, University of British Columbia, Vancouver Kun TangMChinaResearch Center for Public Health, Tsinghua University Medical School, Beijing Alison Morgan (representing MoNITOR)FAustraliaNossal Institute for Global Health, Melbourne School of Population and Global Health, University of Melbourne, MelbourneYoung professionals Charity GiyavaFZimbabweWomen Deliver Dakshitha WickremarathneMSri LankaYouth Advocacy Network, Sri Lanka Diana YeungFUSAJohns Hopkins Bloomberg School of Public Health, Baltimore Open table in a new tab The GAMA Advisory Group had their first meeting from November 28–30, 2018, in Geneva, Switzerland, and considered the current landscape of adolescent health measurement, including key surveys such as the Demographic and Health Surveys [[10]United States Agency for International DevelopmentThe DHS program.https://dhsprogram.com/Date: 2018Date accessed: December 3, 2018Google Scholar], the Multiple Indicator Cluster Survey [[11]UNICEFMultiple Indicator Cluster Surveys.http://mics.unicef.org/Date: 2018Date accessed: December 4, 2018Google Scholar], the Health Behavior in School-Aged Children [[12]HBSC International Coordinating Centre, University of GlasgowHealth behaviour in school-aged children.http://www.hbsc.org/Date: 2018Date accessed: December 1, 2018Google Scholar], the Global School-Based Student Health Survey [[13]World Health OrganizationGlobal School-Based Student Health Survey (GSHS).https://www.who.int/ncds/surveillance/gshs/en/Date: 2018Date accessed: December 5, 2018Google Scholar], and the Global Early Adolescent Study [[14]World Health OrganizationJohns Hopkins Bloomberg School of Public Health, Global Early Adolescent Study.http://www.geastudy.org/Date: 2018Date accessed: December 5, 2018Google Scholar], initiatives to improve mortality data for adolescents and measurement around mental health, nutrition, sexual and reproductive health, substance use, and violence. The group also reviewed existing indicators for adolescent health, facilitated by a mapping of key initiatives and indicator compilations [2Every Woman Every ChildThe global strategy for women's, children's and adolescents' health (2016-2030).2015Google Scholar, 4Patton G.C. Sawyer S.M. Santelli J.S. et al.Our future: A Lancet commission on adolescent health and wellbeing.Lancet. 2016; 387: 2423-2478Abstract Full Text Full Text PDF PubMed Scopus (1519) Google Scholar, 5Inter-Agency and Expert Group on Sustainable Development Goal IndicatorsRevised list of global sustainable development goal indicators.2017Google Scholar, 15Countdown to 2030Women's, children's and adolescents' health.http://countdown2030.org/Date: 2018Date accessed: December 3, 2018Google Scholar, 16Family Planning 2020FP 2020.https://www.familyplanning2020.org/Date: 2018Date accessed: December 4, 2018Google Scholar, 17UNICEFAdolescent country tracker.https://data.unicef.org/resources/adolescent-country-tracker/Date: 2018Date accessed: December 4, 2018Google Scholar, 18World Health OrganizationGlobal reference list of 100 core health indicators (plus health-related SDGs). World Health Organization, Geneva, Switzerland2018Google Scholar, 19World Health OrganizationGlobal reference list of health indicators for adolescents (aged 10-19 years). World Health Organization, Geneva, Switzerland2015Google Scholar]. Several shortcomings with current approaches to adolescent health measurement were identified: First, indicators, their definitions and assessment methods across indicator frameworks are inconsistent, poorly harmonized with data availability, and incompletely aligned to needs. For example, adolescent overweight and obesity, a well-recognized population health risk for future and intergenerational health [[20]Patton G.C. Olsson C.A. Skirbekk V. et al.Adolescence and the next generation.Nature. 2018; 554: 458-466Crossref PubMed Scopus (181) Google Scholar], was inconsistently measured across indicator frameworks and notably missing from the SDGs. Second, age- and sex-disaggregated data for adolescents are often lacking, making the use of the data for program planning difficult. Third, current measurement does not evenly address some adolescent subgroups, for example, out-of-school, in humanitarian settings, boys, migrants, young people of diverse gender identity, incarcerated adolescents, and ethnic and religious minorities. Fourth, topic areas with data gaps included mental health, injury, positive measures of adolescent health and well-being, and measures of sexual and reproductive health among unmarried adolescents and of sensitive nature where more qualitative research would be needed to move toward quantitative measures. Fifth, the link between global and national indicators, as well as between indicators and programming at national and subnational levels is often missing. Sixth, selection of indicators may be dictated by availability of data rather than the most important adolescent health issues. Seventh, data collection tools or administrative systems delivering data are often not well designed for adolescents. For example, registration of deaths drawn from health facilities will largely underestimate adolescent deaths, such as deaths from road traffic, that occur in communities. The overarching goal of GAMA is to define a core set of adolescent health indicators by mid-2020 to converge data collection and reporting efforts. To achieve this, GAMA's initial work plan will concentrate around two key tasks carried out in collaboration with country partners and relevant organizations to ensure the work is relevant and recognized: The first is to define a conceptual framework with priority areas for adolescent health measurement globally, considering what needs to be measured from the perspectives of young people, policymakers, healthcare practitioners, and programmers, and taking into account the disease burden, opportunity for intervention, drivers of health inequality, and different contexts of various regions. Building on this, the second task will map existing indicators and available data of sufficient quality and coverage against the defined priorities. This process will help define indicators that are aligned with the priority areas but also identify data gaps. GAMA's work is documented on a Web site that will be available by May 2019 on WHO's home pages and will be further disseminated through publications and other reporting mechanisms of the involved UN agencies. The GAMA Advisory Group acknowledges several challenges, including the tension of defining a core set of indicators while capturing the important differences that exist across the developmental continuum, the varying pattern of health needs and opportunity for response across different settings, and the important differences across genders. The task is large, but without agreement on core indicators, our efforts to address adolescent health are likely to be inefficient and ineffective, compromising the health of our young people, and all our futures. The Global Action for Measurement of Adolescent Health initiative is funded by the Bill and Melinda Gates Foundation.